Here are 2021's most improved players

September 12th, 2021

Every season offers an opportunity for improvement. This season perhaps has offered greater opportunity than most, coming on the heels of a shortened 2020 campaign that was anything but typical.

Many players have taken advantage. Using Baseball Savant’s year-to-year changes leaderboard, here are 11 players -- seven hitters and four pitchers -- who have made particularly notable gains in a certain category.

All stats are through Saturday's games.


Hard-hit rate: , Reds
Change: +17.8 points

Votto’s 2021 resurgence, at the age of 37, has been one of the best stories of the season. While he never lost his on-base ability, Votto’s power had cratered from 2018-20 (.420 slugging), and he called last year “rock bottom.” But in 2021, the six-time All-Star has “rediscovered how to hit” by focusing on driving the ball. That would be far easier said than done for most -- but most hitters are not Joey Votto. While his strikeout rate is up, that’s been a worthwhile trade-off for Votto lifting his hard-hit rate from 35.7% to 53.5% (easily his highest since Statcast began tracking in 2015). Votto’s season total of 52 barrels already represents his highest in that span, and he just locked up the third 30-homer campaign of his career.

Sweet-spot rate: , Orioles
Change: +13.5 points

Every season introduces us to new stars who emerge seemingly out of nowhere, and nobody fits that role better this year than Mullins, who wound up as the AL’s starting center fielder in the All-Star Game. Closing in on a 30-30 season, Mullins ranks in the top 10 among position players in FanGraphs WAR -- this from a guy who carried a .342 career slugging percentage into Opening Day. One key to Mullins’ success has been replacing a lot of ground balls with line drives and fly balls. His sweet-spot rate -- how often a batted ball is in the ideal launch angle range (8-32 degrees) -- has jumped all the way from 23.4% to 36.9%, helping make him a power threat for the first time.

Barrel rate: , Angels
Change: +12.5 points

Barrel rate measures how often, when a hitter puts the ball in play, they do so with the sort of optimal exit velocity and launch angle that tends to produce extra-base hits. It’s not as if Ohtani struggled in that department before, but in 2021, he’s been on another planet. Not only does he lead MLB qualifiers, but his 23.2% barrel rate is currently the second-best by any player in a season on record (since 2015), trailing only Aaron Judge’s 25.7% from 2017. Oh, and his barrel rate allowed in his side gig as an elite pitcher? Less than three times lower (6.9%).

Whiff rate: , A’s
Change: -11.9 points

As’s Matt Kelly detailed recently, Olson has done something incredibly difficult in 2021, increasing his slugging while also slashing his strikeouts in historic fashion. It’s a combo just about nobody has managed in recent history. How has Olson cut down on his K’s to such a degree? While he hasn’t gotten much more selective, Olson has found a way to get the bat on the ball. In 2020, he ranked in the eighth percentile of MLB hitters in whiff rate (the percentage of swings that produce a miss). In 2021, he’s in the 65th percentile, or well above average.

In-zone swing rate: , Padres
Change: +8.7 points

It’s exhilarating to watch a phenomenal young player who has already been highly successful just continue to get better. We’ve seen it in recent years with Mike Trout, and now we’re seeing it with the likes of Juan Soto and Tatis. In both of his first two seasons, Tatis swung at around 70-72% of pitches in the strike zone (only a bit above the MLB average of about 67-68%). But when you’re as talented as Tatis, why let so many hittable pitches go by? This season, he’s not, going after more than 80% of those offerings and ranking among the top MLB regulars in that category. And not surprisingly, nobody enjoys better production on those in-zone swings.

Chase rate: , Astros
Change: -8.3 points

If there were any questions about Correa’s status as a star player and top pending free agent in the wake of the Astros’ sign-stealing scandal and Correa’s own mediocre 2020 production (albeit followed by a torrid postseason), those have been put to rest. The 26-year-old shortstop looks locked in again at the plate (134 OPS+), perhaps because he is once again waiting for his pitch. After two seasons of rising chase rates, up to a career-high 31.8% in 2020, Correa has dropped that to a career-low 23.5%. His walk rate has sprouted in tandem.

Expected SLG: , Cardinals
Change: +181 points

While we’re listing O’Neill here, he’s also among the two biggest gainers in hard-hit rate (+14.6 points) and barrel rate (+9.4 points). And that’s been the key to his 2021 breakout. While O’Neill has always been able to crush the ball, it seemed as though his bottom-of-the-league contact and K rates were holding him back. Instead, O’Neill has kept right on whiffing in 2021 -- actually more than he did in 2020 -- but the quality of contact he does make is so good that it doesn’t really matter. (Only Ohtani and Tatis Jr. get better results on contact). That explains O’Neill’s soaring xSLG (.376 to .557), which factors in that quality of contact in addition to the K’s.


Whiff rate: , Giants
Change: +6.5 points

From 2019-20, Webb posted a 5.36 ERA over 94 innings for the Giants, mostly as a starter. This year, he’s emerged as the homegrown star in a stellar, veteran rotation mostly built via free agency. Since a rocky beginning to 2021, the 24-year-old righty has a 1.65 ERA over his past 15 starts, in which the Giants have gone 14-1. Webb is pulling off a neat trick, increasing his ground-ball rate by nearly 9 points through increased use of his sinker, while also missing a lot more bats by sharpening his slider. Webb’s whiff rate on that pitch alone has climbed from 28.3% to 46.6%.

Zone rate: , Blue Jays
Change: +8.0 percentage points

Roughly a year ago (Aug. 31, 2020), Ray had a 7.84 ERA when the D-backs traded him to the Blue Jays. To say Ray has turned things around since then would be an understatement, with the lefty a serious AL Cy Young Award contender. Pick a category and Ray has probably improved there. But we’re highlighting zone rate because it’s the most glaring change. No pitcher has increased his zone rate more than Ray (42.9% to 50.9%), who had never previously ranked higher than the 32nd percentile in walk rate. Last year, he was in the second percentile. This year? The 77th. Ray has always racked up K’s, and now that he’s finally throwing strikes, it’s all come together.

Expected wOBA: , White Sox
Change: -91 points

Going by ERA, it might seem as though Cease is more or less the same pitcher as in 2020. But he’s not, at all, despite a rough outing Saturday against Boston. Cease was fortunate to get his results last season, posting a low strikeout rate while walking the most batters in the AL. This time around, he’s backed up his success with huge gains in whiff rate on all three of his secondary pitches (slider, curveball, changeup) to support a massive leap in K-rate (13.8 points) that has coincided with a drop in walk rate. In terms of xwOBA, which factors in both of those things in addition to quality of contact, Cease has improved from .387 (fifth percentile) to .296 (65th).

Fastball velocity: , Brewers
Change: +1.7 mph

The Dodgers’ Kenley Jansen has seen a similar bump in his overall velocity, with both his cutter and sinker at their highest point since 2017. But he’s not the only closer on an NL playoff lock working with higher-octane heat this year. Hader’s four-seamer jumped from 94.5 mph to a career-high 96.3 mph, and he’s sustained that over time (96.4 mph since the All-Star break). One possible explanation: evolving usage. Unlike in seasons past, Hader has not pitched more than one inning at a time but seen the mound more often. The four-seamer, which opponents slugged .426 against from 2019-20, has yielded only a .190 mark this year, contributing to Hader’s 1.42 ERA.